A turbine wastegate is typically a valve (e.g., a wastegate valve) that can be controlled to selectively allow at least some exhaust to bypass a turbine. Where an exhaust turbine drives a compressor for boosting inlet pressure to an internal combustion engine (e.g., as in a turbocharger), a wastegate provides a means to control the boost pressure.
A so-called internal wastegate is integrated at least partially into a turbine housing. A wastegate valve plug of an internal wastegate often includes a flat disk shaped surface that seats against a flat seat (e.g., a valve seat or wastegate seat) disposed on a low pressure side of an exhaust bypass opening. In a closed position, such a wastegate valve plug should be seated against the seat (e.g., seating surface) with sufficient force to effectively seal the exhaust bypass opening to prevent leakage of exhaust from a high pressure exhaust supply on one side of the opening to a lower pressure region on the other side of the opening.
Various examples of wastegates and wastegate components are described herein that can optionally provide for improved kinematics, reduced exhaust leakage, etc.